Grin Kits

Want to purchase a conversion kit from Grin but not sure where to start? This page is intended as a solid primer on the various options and should help narrow things down to the kit most suited to your needs.

Basic Kit Choice

Our most popular hub motor conversion systems are the Bafang Mini Geared kits for those wanting a lighweight setup, the higher end eZee kits for those wanting better hill climbing torque and modest speeds, and the direct drive MXUS and Crysatlyte H35 kits for those wanting fast systems with regenerative braking.

In addition to these common options, we also have a number of specialized kits for niche applications; such as the SAW20 and NSM kits with 75mm axles folding bikes, the Crown for high power offroad bikes, and the Stokemonkey mid-drive for cargo bikes. The TDCM IGH kit is a high-end direct drive motor with a 5-speed internal gear hub all in one package, while the 9C+ offers a budget conversion of great value. We also have the G60 rear motor for fatbike conversions with 175-190mm rear axles. Here’s a summary breakdown of the current packages that we've put together at Grin, from smallest to largest.

Crystalyte NSM

Quick Specs

Motor Weight

2.7 kg

Typ. Power

200-400 W

Motor Type

Direct Drive

Wheel Sizes

16" (ISO349) Front Only

NSM Kit: The Crystalyte NSM is the smallest direct-drive hub motor on the market and is specifically tailored for Brompton and Tikit folding bikes, with a narrow 75mm axle length to fit with no fork spreading. Available front only, unlaced and in 16” ISO349 rims.

Crystalyte SAW20

Quick Specs

Motor Weight

3.4 kg

Typ. Power

250-500 W

Motor Type

Direct Drive

Wheel Sizes

16", 20" Front Only

SAW20 Kit:This hub is suitable for folding bikes with 75mm forks where the power output of NSM isn’t quite adequate. It’s larger in diameter and heavier but maintains the narrow profile as the NSM. Comes laced 16” and 20” rims, allowing it to work with most 20” Dahon/TERN bikes along with the Tikit and Brompton.

Bafang Mini Geared

Quick Specs

Motor Weight

2.55 kg

Typ. Power

250-500 W

Motor Type

Geared

Wheel Sizes

Unlaced Front / Rear

Bafang G311/G310 Geared Kit: These are a smallish geared motors that are well suited for people who want a more minimal level of assistance than the eZee hub. Being a geared kit, they freewheels when not in use, and being lightweight they have little effect on the characteristics of a bike. The G01 is a front motor with conventional spur gears that we have discontinued and replace with the quiter front G311's. The G310 is a rear cassette motor with helical gears. Both are stocked unlaced in a fast and standard speed windings.

G60 Fatbike

Quick Specs

Motor Weight

4.2 kg

Typ. Power

500-1000 W

Motor Type

Geared

Wheel Sizes

Unlaced Rear Only

G60 Fabtike Kit: The Bafang G60 is a rear geared hub motor specifically engineered for fatbikes with extra wide rear dropouts. It uses a cassette freehub system and has a power and torque output that comes close to that of the eZee hub motors.

eZee

Quick Specs

Motor Weight

3.8 kg

Typ. Power

500-1000 W

Motor Type

Geared

Wheel Sizes

20",26",700c Front and Rear

eZee Kit: The eZee system is our popular high performance geared motor setup, and has about twice the power and torque capability of the Outrider motor (500-1000 watts), making it better suited for steeper climbs and cargo hauling. The ~4kg motor is available in both front and rear options, and comes prelaced in 20”, 26”, and 700c wheels with a Schwalbe Marathon Plus tire too

Stokemonkey

Quick Specs

Motor Weight

5.1 kg / 3.3 kg

Typ. Power

400-800 W

Motor Type

Mid-Drive

Compatilbity

Cargo Bikes

Stokemonkey Kit: This is a simple mid-drive drive setup specific to cargo bikes which drives through a tandem crankset, allowing the motor to take advantage of the variable bicycle gearing. It mounts on most longtail bikes (Yuba Mundo, Edgerunner, Big Dummy) and bakfiets (Cetma, Long John), and has better efficiency than a hub motor when carrying heavy loads up steep grades. Both a burly direct drive and lighter geared motor option are available.

Cycle Stoker

Quick Specs

Motor Weight

5.1 kg / 3.3 kg

Typ. Power

400-800 W

Motor Type

Mid-Drive

Compatilbity

EdgerunnerYuba Mundo

Cycle Stoker Kit: This variant of the Stokemonkey system drives on the right via a 2-speed Patterson crankset, allowing for much higher pedal assist speeds than most other mid-drives. Unlike the classic Stokemonkey, it has pedal torque sensing capability and freewheels so that the motor doesn’t force the cranks to turn. The motor mounting system is particular for each bik frame, and at present there are options for the Xtracycle Edgerunner and Yuba Mundo cargo bikes. Both a burly direct drive and lighter geared motor option are available.

TDCM IGH

Quick Specs

Hub Weight

6.5 kg

Typ. Power

500-1000 W

Motor Type

Direct Drive

Wheel Sizes

UnlacedRear Only

TDCM Internal Gear Hub Kit:The TDCM IGH hub features a direct drive motor with an internal 5 speed Sturmey Archer hub for the human transmission, so you get in one clean package a 5 speed gear hub and a powerful motor. It's a great option for people wanting to do conversions on single speed bikes without a derailleur. This motor is manufactured in Taiwan and the quality and build standards are excellent when compared to most chinese motors. It is also sealed and statorade compatible.

Nine Continent 27XX

Quick Specs

Motor Weight

6.2 kg

Typ. Power

500-1000 W

Motor Type

Direct Drive

Wheel Sizes

UnlacedFront/Rear

Nine Continent + Kit:Nine Continent is a company that normally makes hub motors in high volume at low prices for the domestic China market. However, we've been able to work with them to produce a 9C+ series of direct drive motors that uses 0.35mm laminations for reduced drag, and is sealed for Statorade with an injection hole under the disk screw. The mechanical design of these motors as bicycle hubs is so so (disk alignment and caliper clearance are pretty bad, some spoke flange wobble is common) but their performance as efficient direct drive motors is excellent. We have them available unlaced in front and rear in 3 different winding speeds. Excellent for those on a budget.

MXUS 300X

Quick Specs

Motor Weight

6.4 kg

Typ. Power

600-1200 W

Motor Type

Direct Drive

Wheel Sizes

UnlacedRear Only

MXUS Kits:MXUS is well known in the forums for their more powerful 45mm wide hub motors, but these are too large to fit in standard bicycle dropouts. We've had them produce a rear motor version for us with a narrower stator that fits in standard 135mm dropouts, uses cassette freehubs instead of freewheels, has a side axle exit for the motor cable, and is sealed for Statorade. The build quality is better than Nine Continent, and they feature the same 0.35mm laminations and Statorade compatibility of our 9C+ hub series. We stock them in a standard (3006) and faster (3005) winding option.

Crystalyte H 35 Series

Quick Specs

Motor Weight

7.5 kg

Typ. Power

600-1200 W

Motor Type

Direct Drive

Wheel Sizes

20", 24", 26"and Unlaced Front and Rear

Crystalyte H Kit: The H35 series from Crystalyte is a motor has been our standard direct drive hub motor, and the 35mm wide stator and magnets gives it about 30-50% more torque than most inexpensive hubs with 24-27mm magnets, while better design allows it to fit disk brakes both on the front and rear. The motors have some heft and are well suited for fast and powerful ebike setups. Being direct drive they are quiet and capable of regenerative braking, but they also have somewhat higher drag resistance than less powerful direct drive motors. Rear motors are for threaded freewheels only.

Crystalyte The Crown

Quick Specs

Motor Weight

9.2 kg

Typ. Power

1000-3000 W

Motor Type

Direct Drive

Wheel Sizes

24", 26", UnlacedRear Only

Crystalyte Crown:The largest motor that we have on hand is The Crown series from Crystalyte, which is suitable for setups that want to ride more like an electric moped. The Crown TC40 motors are huge, and are so wide that they only fit a single speed freewheel on the rear. There is also a narrower TC30 option that does fit 7 speeds in a 135mm dropout at the expense of less power. They are commonly used on hefty downhill bikes with full suspension, and run plenty of power with 48V to 72V batteries.

Benefits of a Hub Motor

Hub motors are the most versatile and easiest way of converting a bike or trike over to electric assist. Unlike mid-drive systems such as the Bafang BBSHD, they don't put any additional stress on your existing drivechain and operate with complete independence of your pedal transmission. If your chain breaks, derailleur snags, cogs gets loaded in snow etc. the hub motor will continue to propel the bike even when your legs can't. Please have a look at our Why Hub Motors article for a more detailed explanation on the benefits of hub motor systems, especially for commuter ebikes.

Broadly speaking, there are two classes of hub motors, geared and direct drive. And each of those motor types are available for either the front or the rear wheel.

Geared vs Direct Drive

In a geared hub, the motor spins internally at a high RPM and a planetary gear transmission reduces this to the low RPM of the bike wheel. This allows for a relatively small electric motor to provide substantial wheel torque. Geared hub motors usually weight between 2-4kg and are small in diameter, allowing them to remain pretty discrete on the bike. For a number of reasons, almost all geared motors also include a freewheeling clutch so that the wheel will spin freely and not turn the motor over if you are coasting.

In a direct drive hub motor, there hub IS the motor, so there is no internal gearing. The wheel RPM is the same as the motor RPM. This has enormous advantages in terms of simplicity with no moving parts inside, but in order to achieve adequate torque the direct drive motors need to be fairly large in diameter and heavy. They are typically between 4-9kg and over 20cm (8") diameter. Direct drive motors don't have a clutch, allowing them to do regenerative braking, but this also means that there is some motor drag while coasting as the magnets are always moving past the stator iron.

Pros of Geared Motor

Pros of Direct Drive

⦁ Discrete smaller diameter

⦁ Better high speed efficiency

⦁ Light Weight

⦁ Regenerative braking

⦁ Freewheeling

⦁ Silent operation

⦁ Better hill climbing efficiency

⦁ No moving parts to fail

In general, we find that geared motors are most often preferred by people who value their smaller size and weight, who require a hub with good efficiency during hill climbing, and for whom the ability to coast with zero drag outweighs the benefits of regenerative braking.

Direct drive hub motors generally shine most in applications where high speed is needed, where regenerative braking is useful, where complete silence is paramount, and where the additional motor weight is not seen as too problematic.

Regenerative Braking?

Regenerative braking involves using the motor as a brake to assist in slowing the bike down without wearing your mechanical brakes. This typically results in a 3-8% increase in your range from recaptured energy and a massive reduction in the frequency with which you need to adjust and replace your brake pads. There is no downside or tradeoff whatsoever to having regen if you have a direct drive hub motor, and if you have a geared or mid-drive motor it's not an option so there's no point mulling over it.

All of our Grinfineon and Phaserunner controllers have variable regenerative braking with a V3 Cycle Analyst, allowing you to modulate the braking intensity with your throttle. Most standard Chinese controllers with regen will just have a fixed level of regen when the brakes are pressed.

Front vs Rear (or Both)?

The next big question for hub motor selection is whether to put the motor on the front or the rear of the bike. There is a TON of misinformation on the internet and endless-sphere in particular which says you should always choose a rear hub motor and that front hub motors are dangerous/unstable/ill advised. This is complete nonsense, and in fact for most conversions we recommend a front hub unless there is a compelling reason to put the motor on the rear. There is also generally no problem at all installing a hub motor on a bike with suspension forks, carbon forks or whatever. So long as you have a properly installed torque arm so that the axle rotation is not spreading the dropouts, the pulling forces that a motor puts on a fork are WAY smaller than the forces present when slamming on the front brakes or hitting a pothole.

The benefits of a front hub are as follows:

No conflict or change to your drivechain

Ability use internal gear hubs on the rear

Simpler installation

Better weight distribution if battery is on the rear

The main downside of a front hub relates to the fact that on most bicycles, a majority of the rider weight is on the rear wheel rather than the front wheel, so the amount of traction available on the front wheel is not as high and it can be possible for the wheel to skid out at full throttle. Riding on pavement this only becomes an issue at pretty high power levels (>1500 watts), but when climbing hills on loose gravel or dirt roads, you can end up with the front wheel skidding pretty easily even at fairly modest powers unless you deliberately lean over the handlebars.

Downsides to a Front Hub:

Limited traction for high power (>1500 watts) or loose gravel roads

Not entirely discrete, especially direct drive

For rear installations, the motor is more discretely buried with the cogs and pannier bags, and it is possible to run at very high power levels without loosing traction. However, the motor must also tie into the mechanical drivechain.

Downsides to a Rear Hub:

No opportunity to use internal gear hubs (unless you get the TDCM IGH kit)

From our perspective, the decision of front or rear motors is fairly easy. You'd generally choose a front hub for ease of installation and versatility, unless your vehicle design doesn't allow it (eg tadpole trike), or your ride situation would have traction issues (dirt road hill climbing or very high power), or you just figure that, justified or not, you want the motor on the back. There are fewer compatibility issues with rear hub motors now that we have more options using cassette freehubs and proper disk alignment, such as the G310 and MXUS kits.

Dual Hub Motors

Dual front/rear hub motors on a bike is an excellent way to achieve higher power levels than a single hub motor can produce, and is especially useful in cargo bike or load hauling applications. When you run two brushless motor systems on the bike, each motor requires it's own motor controller (there is no way around this) but the throttle signal would typically be split to run both motors equally. For systems running two motors with a V3 Cycle Analyst, we have a dual motor CA shunt that provides a plug and play wiring setup, while for those without a CA we have a simpler dual controller throttle splitter cable for the same purpose.

Most often you would use matching motors for the front and rear, ex dual eZee motors, dual Crystalyte, dual 9C+, and the power would always be split 50:50 between the two motors. However, there are cases where running different motors makes sense too. A popular one would be a rear eZee motor and a front direct drive like the 9C+. The eZee motor would do much of the grunt of the work on steep hill climbs and the likes, while the 9C+ motor provides regenerative braking and runs at good efficiency when riding on the flats.

Speed, Power and Range

In general, larger and heavier motors will be able to handle higher power levels for longer time periods before overheating. See our motor power info page for more details.

The speed that you'll have with a given motor depends on the motor winding option, wheel diameter, and battery voltage, it is not an intrinsic property of the motor. You can increase the speed by either increasing your battery voltage (say running 48V instead of 36V), or choosing a higher RPM motor winding (like the eZee 350rpm model rather than 250rpm model) and keeping the voltage the same. All of our hub motors can be configured to spin as fast or as slow as you like. but to move a bike quickly requires a lot of power, especially going uphill, and this will limit the ability of small motors to make you move fast. At the bottom of each kit page there is a preview line showing the unloaded speed and off-the-line thrust for your particular motor choice, wheel diameter, and motor controller which you can use as a guideline.

Please understand that the unloaded speed is NOT the speed at which you will travel, that is the speed that the motor will spin when it is lifted off the ground, you'll need to use our Hub Motor Simulator to get the exact behavior for your setup with different rider weights, hill grades etc:

The range of an ebike has almost nothing to do with your motor selection and almost everything to do with the size of your battery pack and how heavily you rely on the electric assist. This is discussed in detail on our battery kits info page.

Controller Selection

On most of our direct drive motor kits, we give multiple controller options that we think are suitable for use with the motor. Controllers are generally defined by their battery current limit, which represents the highest current they will draw from a battery pack before their internal rollback kicks in. The higher current motor controllers will allow more power into the motor, giving more torque for hill climbing etc. But this also puts more stress on the battery pack, and can make the motor more prone to overheat. We usually recommend the smallest current controller that will meet your power needs.

The Grinfineon 20A, 25A, and 35A controllers all work with 36V to 52V nominal batteries and represent excellent value with features rarely found on generic devices. The eZee kit includes it's own eZee motor controller that is well suited for the high electrical RPM's of this geared motor. For use 60V and 72V battery systems, only the Phaserunner and 40A Grinfineon are up to the task.

The Phaserunner differs from the Grinfineon controllers in that it is a fully programmable field oriented controller, designed and made in Canada, with features and compactness rarely seen in the ebike space. Both the phase and battery current limits and voltage rollbacks can all be customized with our software suite to match your motor and battery limits. It's a premium device suited for those who want the best of the best and aren't intimidated by a technical product.

Pedal Assist vs Throttle?

All of our conversion kit packages are listed either as a "Basic Throttle" package with your choice of display options, or an "Advanced PAS" kit which requires the V3 Cycle Analyst.

A throttle is the most obvious means of controlling the power on an ebike. You either push a lever or twist a grip, and the more you twist it the more power you have from the motor. It's simple and works great, but after a while you can find yourself suffering a bit of throttle fatigue especially on longer trips.

We have thumb throttles, twist throttles, and half twist throttles. Usually people with twist grip shifters will opt for a thumb throttle, while those with lever shifters could choose between a thumb style or a twist grip. The half twist throttle is safer than the full twist since you are less likely to accidentally turn the throttle while grabbing or walking the bike, but there are some who really like the feel the full grip rotating like on a motorcycle.

With a basic pedal sensor (PAS), the electronics are configured to automatically power the motor when it detects that you are pedaling. Once you stop pedaling, the motor assistance stops. The amount of power assist is configured via the V3 Cycle Analyst, and there are various options (pot, 3 position switch, digital aux) that let you easily increase or decrease the PAS assistance while riding. But the assistance does not change with your pedal effort, as the sensor only knows how fast you are turning the cranks, not how much force you are applying.

With a torque sensor pedal assistance, there is sensor measuring how much force the rider is putting on the pedals. That allows you the rider to control the ebike motor with your legs; the harder you pedal the more power you get from the hub. This kind of control can feel very slick and helps encourage more human power input, since you are made to 'earn' your motor power. The most common torque sensors (Sempu, TDCM, NTCE) replace your bottom bracket with one that has a built-in sensor module, and while a bit complicated to install the end result is very slick. For more information on PAS sensors and Torque sensors, see our guide to Advanced PAS Kits and our more general Learning Page on Pedal Assist Systems.

All of our controllers will accept just a simple throttle input without any kind of display. But to use a PAS or Torque sensor, you need a V3 Cycle Analyst, which acts as the interface between the various sensor signals and the motor controller, and you should choose the "advanced PAS" kit option to see these. Even if you have a PAS or Torque sensor, we still recommend having a throttle installed on the bike too since there are times when it can be quite handy to have that as a backup means to power the motor.

Ebrake Cutoffs?

An ebrake is a switch built into your brake levers which sends a signal to your motor controller or V3 Cycle Analyst in order to automatically cut power when you are braking. While it is sometimes touted as an important safety feature, in practice we don't think these are generally necessary for that reason. The mechanical brakes on a bike can easily overpower a motor if for some reason you were to throttle and brake at the same time. However, if you have a PAS assist system then a brake cutoff can be handy to momentarily removing the automatic assistance while you are pedaling. Where ebrake levers really shine is in setups that have a direct drive hub motor with regenerative braking. In these cases, we recommend installing the brake cutoff on the opposite lever as your throttle, so that it is easy to use one hand to enable regen and the other to modulate it with the throttle.

For standard mechanical brake systems, we have the inexpensive Wuxing and Tektro complete ebrake levers available. If you have hydraulic brakes and/or want to preserve your existing brake levers rather than replace them, then the universal tripwire cutoff sensor that can be attached to the brakes you've already got installed.

Torque Arms

We give the option to select a torque arm with most of the hub motor kits. The three exceptions are the Bafang G01, G310, and TDCM IGH motors. The Bafang motors use keyed washers for anti-rotation support and have a round axle on the threads so is not compatible with torque arms, while the TDCM IGH hub includes a solid forged steel anti-rotation block which similarly engages with the slotted rear dropout.

For information on whether you need a torque arm in your setup and how to select the best model, see our torque arms info page

Tidy Wiring Kit

You can make your DIY ebike conversion look as slick and clean as a commercial ebike by simply paying close attention to your cable routing and using the velcro sleeves, spiral wrap, and zip ties included in our tidy wiring package. Homemade ebikes have something of a reputation for being a rats nest of wires and exposed connectors but there is no need for this.

Temperature Sensors and Statorade

One of the benefits of getting a conversion kit from Grin is that we have pioneered the inclusion of motor temperature sensors and Statorade compatibility for most of our direct drive motor series. This allows for you to push the envelope of sustained power and torque output from a given motor without risk of damaging the hub. The Statorade allow for heat in the motor to escape more easily, increasing by about 30-50% the continuous continuous torque capability, and the temperature sensor allows the system to automatically scale back power before the motor gets hot enough to be damaged.

These features are not required for people using the hub motors within their nominal power range, but for those who like to push the envelope a bit they are golden. The temperature sensor just requires an extension cable to link the thermistor in the motor up to the CA3.

Legal Compliance

Any setup that includes a Cycle Analyst can be configured via the Cycle Analyst to have custom speed limits and power limits in order to be compliant with the various electric bicycle regulations in different parts of the world. So it is perfectly possible to run a fast and powerful offroad ebike, and then have it throttled to say 250 watts and 24kph to meet the European electric bike limits when riding on road. But it is up to you as the person building and assembling the ebike to configure this. As supplied there is no intrinsic limiting enabled.